An example of anode used for a solid electrolytic capacitor is disclosed in the Patent Document 1 described below. As shown in FIG. 15A of the present application, the conventional anode includes a metal plate 91 and a porous sintered body 94 formed on the metal plate. The metal plate 91 and the sintered body 94 are made of metal having valve action (hereinafter simply referred to as “valve metal”). As shown in FIG. 15B, the illustrated anode X is prepared by applying a material 93 containing valve metal powder 92 onto the metal plate 91 and then sintering the material 93. With this method, the sintered body 94 having a desired size in plan view and a relatively small thickness can be easily formed. This means that the capacitance, the ESR (equivalent series resistance) and the ESL (equivalent series inductance) of the solid electrolytic capacitor in which the anode X is used can be easily adjusted.
Patent Document 1: JP-A-S59-219923
Recently, various electronic devices tend to be reduced in size. Accordingly, a solid electrolytic capacitor to be incorporated in such an electronic device needs to be small. On the other hand, to cope with an increase in power supply, the capacitance of a capacitor needs to be increased. In a solid electrolytic capacitor using the above-described anode A, by increasing the capacitance per unit volume of the sintered body 94, the capacitance of the capacitor can be increased without increasing the size of the capacitor. In the process of manufacturing the anode X, a binder solution, for example, contained in the material 93 volatilizes in sintering the material, and the powder 92 left on the anode metal plate 91 is sintered to form the porous sintered body 94. In this process, any particular processing for increasing the density of the porous sintered body 94 is not performed. Therefore, in the anode X, the capacitance per unit volume of the porous sintered body 94 is not sufficiently high, so that the need for small size and large capacitance of the solid electrolytic capacitor cannot be properly satisfied.